Dynamic bandwidth allocation to transmit a wireless protocol across a code division multiple access (CDMA) radio link

ABSTRACT

A technique for transmission of wireless signals across CDMA radio links. Bandwidth is allocated dynamically within a session to specific CDMA subscriber unit based upon data rate determinations. Specifically, a dynamic bandwidth allocation algorithm operates from limits calculated based upon available ports per subscriber, expected user bandwidth, and parallel user bandwidth versus throughput. Provisions for priority service, unbalanced forward and reverse spectrum utilization, voice prioritization, and band switching are also made.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation of pending U.S. applicationSer. No. 08/992,760 filed Dec. 17, 1997 entitled “Dynamic BandwidthAllocation to Transmit a Wireless Protocol Across a Code DivisionMultiple Access (CDMA) Radio Link,” which itself claims the benefit ofU.S. Provisional Application No. 60/050,338 filed Jun. 20, 1997 entitled“Dynamic Bandwidth Allocation to Transmit a Wireless ISDN ProtocolAcross a Code Division Multiple Access (CDMA) Radio Link” and U.S.Provisional Application No. 60/050,277 filed Jun. 20, 1997 entitled“Protocol Conversion and Bandwidth Reduction Technique ProvidingMultiple nB+D ISDN Basic Rate Interface Links Over a Wireless CodeDivision Multiple Access Communication System,” the entire teachings ofall of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] The increasing use of wireless telephones and personal computersby the general population has led to a corresponding demand for advancedtelecommunication services that were once thought to only be meant foruse in specialized applications.

[0003] For example, in the late 1980's, wireless voice communicationsuch as available with cellular telephony had been the exclusiveprovince of the businessman because of expected high subscriber costs.The same was also true for access to remotely distributed computernetworks, whereby until very recently, only business people and largeinstitutions could afford the necessary computers and wireline accessequipment.

[0004] However, the general population now increasingly wishes to notonly have access to networks such as the Internet and private intranets,but also to access such networks in a wireless fashion as well. This isparticularly of concern for the users of portable, computers, laptopcomputers, hand-held personal digital assistants and the like who wouldprefer to access such networks without being tethered to a telephoneline.

[0005] There still is no widely available satisfactory solution forproviding low cost, high speed access to the Internet and other networksusing existing wireless networks. This situation is most likely anartifact of several unfortunate circumstances. For example, the typicalmanner of providing high speed data service in the business environmentover the wireline network is not readily adaptable to the voice gradeservice available in most homes or offices. In addition, such standardhigh speed data services do not lend themselves well to efficienttransmission over standard cellular wireless handsets.

[0006] Furthermore, the existing cellular network was originallydesigned only to deliver voice services. At present, the wirelessmodulation schemes in use continue their focus on delivering voiceinformation with maximum data rates only in the range of 9.6 kbps beingreadily available. This is because the cellular switching network inmost countries, including the United States, uses analog voice channelshaving a bandwidth from about 300 to 3600 Hertz. Such a low frequencychannel does not lend itself directly to transmitting data at rates of28.8 kilobits per second (kbps) or even the 56.6 kbps that is nowcommonly available using inexpensive wire line modems, and which ratesare now thought to be the minimum acceptable data rates for Internetaccess.

[0007] Switching networks with higher speed building blocks are just nowcoming into use in the United States. Although certain wirelinenetworks, called Integrated Services Digital Networks (ISDN), capable ofhigher speed data access have been known for a number of years, theircosts have only been recently reduced to the point where they areattractive to the residential customer, even for wireline service.Although such networks were known at the time that cellular systems wereoriginally deployed, for the most part, there is no provision forproviding ISDN-grade data services over cellular network topologies.

[0008] ISDN is an inherently circuit switched protocol, and was,therefore, designed to continuously send bits in order to maintainsynchronization from end node to end node to maintain a connection.Unfortunately, in wireless environments, access to channels is expensiveand there is competition for them; the nature of the medium is such thatthey are expected to be shared. This is dissimilar to the usual wirelineISDN environment if which channels are not intended to be shared bydefinition.

SUMMARY OF THE INVENTION

[0009] The present invention provides high speed data and voice serviceover standard wireless connections via an unique integration of ISDNprotocols and existing cellular signaling such as is available with CodeDivision Multiple Access (CDMA) type modulated systems. The presentinvention achieves high data rates through more efficient allocation ofaccess to the CDMA wireless channels. In particular, a number ofsubchannels are defined within a standard CDMA channel bandwidth, whichis normally necessary to support the ISDN protocol, such as by assigningdifferent codes to each subchannel. The instantaneous bandwidth needs ofeach on-line subscriber unit are met by dynamically allocating multiplesubchannels of the RF carrier on an as needed basis for each session.For example, multiple subchannels are granted during times when thesubscriber bandwidth requirements are relatively high, such as whendownloading Web pages and released during times when the line content isrelatively light, such as when the subscriber is reading a Web pagewhich has been previously downloaded or is performing other tasks.

[0010] Subchannel assignment algorithms may be implemented to offervarious levels of priority service to particular subscribers. These maybe assigned based upon available ports per subscriber, expected userbandwidth, service premium payments, and so on.

[0011] In accordance with another aspect of the invention, some portionof the available bandwidth is initially allocated to establish acommunication session. Once the session has been established, if asubscriber unit has no data to present for transmission, namely, if thedata path remains quiescent for some period of time, the previouslyassigned bandwidth is deallocated. In addition, it is preferable thatnot all of the previously assigned bandwidth be deallocated, but ratherat least some portion be kept available for use by an in-sessionsubscriber. If the inactivity continues for a further period of time,then even the remaining portion of the bandwidth can be deallocated fromthe session. A logical session connection at a network layer protocol isstill maintained even if no subchannels are assigned.

[0012] In a preferred arrangement, a single subchannel is maintained fora predetermined minimum idle time for each network layer connection.This assists with more efficient management of channel setup and teardown.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views.

[0014]FIG. 1 is a block diagram of a wireless communication systemmaking use of a bandwidth management scheme according to the invention.

[0015]FIG. 2 is an Open System Interconnect (OSI) type layered protocoldiagram showing where the bandwidth management scheme is implemented interms of communication protocols.

[0016]FIG. 3 is a diagram showing how subchannels are assigned within agiven radio frequency (RF) channel.

[0017]FIG. 4 is a more detailed block diagram of the elements of asubscriber unit.

[0018]FIG. 5 is a state diagram of the operations performed by asubscriber unit to request and release subchannels dynamically.

[0019]FIG. 6 is a block diagram of a portion of a base station unitnecessary to service each subscriber unit.

[0020]FIG. 7 is a high level structured English description of a processperformed by the base station to manage bandwidth dynamically accordingto the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Turning attention now to the drawings more particularly, FIG. 1is a block diagram of a system 100 for providing high speed data andvoice service over a wireless connection by seamlessly integrating adigital data protocol such as, for example, Integrated Services DigitalNetwork (ISDN) with a digitally modulated wireless service such as CodeDivision Multiple Access (CDMA).

[0022] The system 100 consists of two different types of components,including subscriber units 101, 102 and base stations 170. Both types ofthese components 101 and 170 cooperate to provide the functionsnecessary in order to achieve the desired implementation of theinvention. The subscriber unit 101 provides wireless data services to aportable computing device 110 such as a laptop computer, portablecomputer, personal digital assistant (PDA) or the like. The base station170 cooperates with the subscriber unit 101 to permit the transmissionof data between the portable computing device 110 and other devices suchas those connected to the Public Switched Telephone Network (PSTN) 180.

[0023] More particularly, data and/or voice services are also providedby the subscriber unit 101 to the portable computer 110 as well as oneor more other devices such as telephones 112-1, 112-2 (collectivelyreferred to herein as telephones 112. (The telephones 112 themselves mayin turn be connected to other modems and computers which are not shownin FIG. 1). In the usual parlance of ISDN, the portable computer 110 andtelephones 112 are referred to as terminal equipment (TE). Thesubscriber unit 101 provides the functions referred to as a networktermination type 1 (NT-1). The illustrated subscriber unit 101 is inparticular meant to operate with a so-called basic rate interface (BRI)type ISDN connection that provides two bearer or “B” channels and asingle data or “D” channel with the usual designation being 2B+D.

[0024] The subscriber unit 101 itself consists of an ISDN modem 120, adevice referred to herein as the protocol converter 130 that performsthe various functions according to the invention including spoofing 132and bandwidth management 134, a CDMA transceiver 140, and subscriberunit antenna 150. The various components of the subscriber unit 101 maybe realized in discrete devices or as an integrated unit. For example,an existing conventional ISDN modem 120 such as is readily availablefrom any number of manufacturers may be used together with existing CDMAtransceivers 140. In this ease, the unique functions are providedentirely by the protocol converter 130 which may be sold as a separatedevice. Alternatively, the ISDN modem 120, protocol converter 130, andCDMA transceiver 140 may be integrated as a complete unit and sold as asingle subscriber unit device 101.

[0025] The ISDN modem 120 converts data and voice signals between theterminal equipment 110 and 112 to format required by the standard ISDN“U” interface. The U interface is a reference point in ISDN systems thatdesignates a point of the connection between the network termination(NT) and the telephone company.

[0026] The protocol converter 130 performs spoofing 132 and basicbandwidth management 134 functions, which will be described in greaterdetail below. In general, spoofing 132 consists of insuring that thesubscriber unit 101 appears to the terminal equipment 110, 112 that isconnected to the public switched telephone network 180 on the other sideof the base station 170 at all times.

[0027] The bandwidth management function 134 is responsible forallocating and deallocating CDMA radio channels 160 as required.Bandwidth management also includes the dynamic management of thebandwidth allocated to a given session by dynamically assigningsub-portions of the CDMA channels 160 in a manner which is more fullydescribed below.

[0028] The CDMA transceiver 140 accepts the data from the protocolconverter 130 and reformats this data in appropriate form fortransmission through a subscriber unit antenna 150 over CDMA radio link160-1. The CDMA transceiver 140 may operate over only a single 1.25 MHZradio frequency channel or, alternatively, in a preferred embodiment,may be tunable over multiple allocatable radio frequency channels.

[0029] CDMA signal transmissions are then received at the base stationand processed by the base station equipment 170. The base stationequipment 170 typically consists of multichannel antennas 171, multipleCDMA transceivers 172, and a bandwidth management functionality 174.Bandwidth management controls the allocation of CDMA radio channels 160and subchannels. The base station 170 then couples the demodulated radiosignals to the Public Switch Telephone Network (PSTN) 180 in a mannerwhich is well known in the art. For example, the base station 170 maycommunicate with the PSTN 180 over any number of different efficientcommunication protocols such as primary rate ISDN, or other LAPD basedprotocols such as IS-634 or V5.2.

[0030] It should also be understood that data signals travelbidirectionally across the CDMA radio channels 160, i.e., data signalsoriginate at the portable computer 110 are coupled to the PSTN 180, anddata signals received from the PSTN 180 are coupled to the portablecomputer 110.

[0031] Other types of subscriber units such as unit 102 may be used toprovide higher speed data services. Such subscriber units 102 typicallyprovide a service referred to as nB+D type service that may use aso-called Primary Rate Interface (PRI) type protocol to communicate withthe terminal equipment 110, 112. These units provide a higher speedservice such as 512 kbps across the U interface. Operation of theprotocol converter 130 and CDMA transceiver 140 are similar for the nB+Dtype subscriber unit 102 as previously described for subscriber unit101, with the understanding that the number of radio links 160 supportsubscriber unit 102 are greater in number or each have a greaterbandwidth.

[0032] Turning attention now to FIG. 2, the invention may be describedin the context of a Open Systems Interconnect multilayer protocoldiagram. The three protocol stacks 220, 230, and 240 are for the ISDNmodem 120, protocol converter 130, and base station 170, respectively.

[0033] The protocol stack 220 used by the ISDN modem 120 is conventionalfor ISDN communications and includes, on the terminal equipment side,the analog to digital conversion (and digital to analog conversion) 221and digital data formatting 222 at layer one, and an applications layer223 at layer two. On the U interface side, the protocol functionsinclude Basic Rate Interface (BRI) such as according to standard 1.430at layer one, a LAPD protocol stack at layer two, such as specified bystandard Q.921, and higher level network layer protocols such as Q.931or X.227 and high level end to end signaling 228 required to establishnetwork level sessions between modes.

[0034] The lower layers of the protocol stack 220 aggregate two bearer(B) channels to achieve a single 128 kilobits per second (kbps) datarate in a manner which is well known in the art. Similar functionalitycan be provided in a primary rate interface, such as used by subscriberunit 102, to aggregate multiple B channels to achieve up to 512 kbpsdata rate over the U interface.

[0035] The protocol stack 230 associated with the protocol converter 130consists of a layer one basic rate interface 231 and a layer two LAPDinterface 232 on the U interface side, to match the corresponding layersof the ISDN modem stack 220.

[0036] At the next higher layer, usually referred to as the networklayer, a bandwidth management functionality 235 spans both the Uinterface side and the CDMA radio link side of the protocol converterstack 230. On the CDMA radio link side 160, the protocol depends uponthe type of CDMA radio communication in use. An efficient wirelessprotocol referred to herein as EW[x] 234, encapsulates the layer one 231and layer two 232 ISDN protocol stacks in such a manner that theterminal equipment 110 may be disconnected from one or more CDMA radiochannels without interrupting a higher network layer session.

[0037] The base station 170 contains the matching CDMA 241 and EW[x] 242protocols as well as bandwidth management 243. On the PSTN side, theprotocols may convert back to basic rate interface 244 and LAPD 245 ormay also include higher level network layer protocols as Q.931 or V5.2246.

[0038] Call processing functionality 247 allows the network layer to setup and tear down channels and provide other processing required tosupport end to end session connections between nodes as is known in theart.

[0039] The spoofing function 132 performed by the EW[x] protocol 234includes the necessary functions to keep the U interface for the ISDNconnection properly maintained, even in the absence of a CDMA radio link160 being available. This is necessary because ISDN, being a protocoloriginally developed for wire line connections, expects to send acontinuous stream of synchronous data bits regardless of whether theterminal equipment at either end actually has any data to transmit.Without the spoofing function 132, radio links 160 of sufficientbandwidth to support at least a 192 kbps data rate would be requiredthroughout the duration of an end to end network layer session, whetheror not data is actually presented.

[0040] EW[x] 234 therefore involves having the CDMA transceiver 140 loopback these synchronous data bits over the ISDN communication path tospoof the terminal equipment 110, 112 into believing that a sufficientlywide wireless communication link 160 is continuously available. However,only when there is actually data present from the terminal equipment tothe wireless transceiver 140 is wireless bandwidth allocated. Therefore,unlike the prior art, the network layer need not allocate the assignedwireless bandwidth for the entirety of the communications session. Thatis, when data is not being presented upon the terminal equipment to thenetwork equipment, the bandwidth management function 235 deallocatesinitially assigned radio channel bandwidth 160 and makes it availablefor another transceiver and another subscriber unit 101.

[0041] In order to better understand how bandwidth management 235 and243 accomplish the dynamic allocation of radio bandwidth, turn attentionnow to FIG. 3. This figure illustrates one possible frequency plan forthe wireless links 160 according to the invention. In particular, atypical transceiver 170 can be tuned on command to any 1.25 MHZ channelwithin a much larger bandwidth, such as up to 30 MHZ. In the case oflocation in an existing cellular radio frequency bands, these bandwidthsare typically made available in the range of from 800 to 900 MHZ. Forpersonal communication systems (PCS) type wireless systems, thebandwidth is typically allocated in the range from about 1.8 to 2.0GigaHertz (GHz). In addition, there are typically two matching bandsactive simultaneously, separated by a guard band, such as 80 MHZ; thetwo matching bands form forward and reverse full duplex link.

[0042] Each of the CDMA transceivers, such as transceiver 140 in thesubscriber unit 101 and transceivers 172 in the base station 170, arecapable of being tuned at any given point in time to a given 1.25 MHZradio frequency channel. It is generally understood that such 1.25 MHZradio frequency carrier provides, at best, a total equivalent of about500 to 600 kbps maximum data rate transmission within acceptable biterror rate limitations.

[0043] In the prior art, it was thus generally understood that in orderto support an ISDN type like connection which may contain information ata rate of 128 kbps that, at best, only about (500 kbps/128 kbps) or only3 ISDN subscriber units could be supported at best.

[0044] In contrast to this, the present invention subdivides theavailable approximately 500 to 600 kbps bandwidth into a relativelylarge number of subchannels. In the illustrated example, the bandwidthis divided into 64 subchannels 300, each providing an 8 kbps data rate.A given subchannel 300 is physically implemented by encoding atransmission with one of a number of different assignable pseudorandomcodes. For example, the 64 subchannels 300 may be defined within asingle CDMA RF carrier by using a different orthogonal Walsh codes foreach defined subchannel 300.

[0045] The basic idea behind the invention is to allocate thesubchannels 300 only as needed. For example, multiple subchannels 300are granted during times when a particular ISDN subscriber unit 101 isrequesting that large amounts of data be transferred. These subchannels300 are released during times when the subscriber unit 101 is relativelylightly loaded.

[0046] Before discussing how the subchannels are preferably allocatedand deallocated, it will help to understand a typical subscriber unit101 in greater detail. Turning attention now to FIG. 4, it can be seenthat an exemplary protocol converter 130 consists of a microcontroller410, reverse link processing 420, and forward link processing 430. Thereverse link processing 420 further includes ISDN reverse spoofer 422,voice data detector 423, voice decoder 424, data handler 426, andchannel multiplexer 428. The forward link processing 430 containsanalogous functions operating in the reverse direction, including achannel multiplexer 438, voice data detector 433, voice decoder 434,data handler 436, and ISDN forward spoofer 432.

[0047] In operation, the reverse link 420 first accepts channel datafrom the ISDN modem 120 over the U interface and forwards it to the ISDNreverse spoofer 432. Any repeating, redundant “echo” bits are removedfrom data received and, once extracted, sent to the forward spoofer 432.The remaining layer three and higher level bits are thus informationthat needs to be send over a wireless link.

[0048] This extracted data is sent to the voice decoder 424 or datahandler 426, depending upon the type of data being processed.

[0049] Any D channel data from the ISDN modem 120 is sent directly tovoice data detection 423 for insertion on the D channel inputs to thechannel multiplexer 428. The voice data detection circuit 423 determinesthe content of the D channels by analyzing commands received on the Dchannel.

[0050] D channel commands may also be interpreted to control a class ofwireless services provided. For example, the controller 410 may store acustomer parameter table that contains information about the customersdesired class of service which may include parameters such as maximumdata rate and the like. Appropriate commands are thus sent to thechannel multiplexer 428 to request one or more required subchannels 300over the radio links 160 for communication. Then, depending upon whetherthe information is voice or data, either the voice decoder 424 or datahandler 426 begins feeding data inputs to the channel multiplexer 428.

[0051] The channel multiplexer 428 may make further use of controlsignals provided by the voice data detection circuits 423, dependingupon whether the information is voice or data.

[0052] In addition, the CPU controller 410, operating in connection withthe channel multiplexer 428, assists in providing the necessaryimplementation of the EW[x] protocol 234 between the subscriber unit 101and the base station 170. For example, subchannel requests, channelsetup, and channel tear down commands are sent via commands placed onthe wireless control channel 440. These commands are intercepted by theequivalent functionality in the base station 170 to cause the properallocation of subchannels 300 to particular network layer sessions.

[0053] The data handler 426 provides an estimate of the data raterequired to the CPU controller 410 so that appropriate commands can besent over the control channel 440 to allocate an appropriate number ofsubchannels. The data handler 426 may also perform packet assembly andbuffering of the layer three data into the appropriate format fortransmission.

[0054] The forward link 430 operates in analogous fashion. Inparticular, signals are first received from the channels 160 by thechannel multiplexer 438. In response to receiving information on thecontrol channels 440, control information is routed to the voice datadetection circuit 433. Upon a determination that the receivedinformation contains data, the received bits are routed to the datahandler 436. Alternatively, the information is voice information, androuted to the voice decoder 434.

[0055] Voice and data information are then sent to the ISDN forwardspoofer 432 for construction into proper ISDN protocol format. Thisassembly of information is coordinated with the receipt of echo bitsfrom the ISDN reverse spoofer 422 to maintain the proper expectedsynchronization on the U interface with the ISDN modem 120.

[0056] It can now be seen how a network layer communication session maybe maintained even though wireless bandwidth initially allocated fortransmission is reassigned to other uses when there is no information totransmit. In particular, the reverse 422 and forward 432 spooferscooperate to loop back non-information bearing signals, such as flagpatterns, sync bits, and other necessary information, so as to spoof thedata terminal equipment connected to the ISDN modem 120 into continuingto operate as though the allocated wireless path over the CDMAtransceiver 150 is continuously available.

[0057] Therefore, unless there is an actual need to transmit informationfrom the terminal equipment being presented to the channel multiplexers428, or actual information being received from the channel multiplexers438, the invention may deallocate initially assigned subchannel 300,thus making them available for another subscriber unit 101 of thewireless system 100.

[0058] The CPU controller 410 may also perform additional functions toimplement the EW[x] protocol 234, including error correction, packetbuffering, and bit error rate measurement.

[0059] The functions necessary to implement bandwidth management 235 inthe subscriber unit 101 are carried out in connection with the EW[x]protocol typically by the CPU controller 410 operating in cooperationwith the channel multiplexers 428, 438, and data handlers 420, 436. Ingeneral, bandwidth assignments are made for each network layer sessionbased upon measured short term data rate needs. One or more subchannels300 are then assigned based upon these measurements and other parameterssuch as amount of data in queue or priority of service as assigned bythe service provider. In addition, when a given session is idle, aconnection is preferably still maintained end to end, although with aminimum number of, such as a single subchannel being assigned. Forexample, this single subchannel may eventually be dropped after apredetermined minimum idle time is observed.

[0060]FIG. 5 is a detailed view of the process by which a subscriberunit 101 may request subchannel 300 allocations from the base station170 according to the invention. In a first state 502, the process is inan idle state. At some point, data becomes ready to transmit and state504 is entered, where the fact that data is ready to be transmitted maybe detected by an input data buffer in the data handler 426 indicatedthat there is data ready.

[0061] In state 504, a request is made, such as via a control channel440 for the allocation of a subchannel to subscriber unit 101. If asubchannel is not immediately available, a pacing state 506 may beentered in which the subscriber unit simply waits and queues its requestfor a subchannel to be assigned.

[0062] Eventually, a subchannel 300 is granted by the base station andthe process continues to state 508. In this state, data transfer maythen begin using the single assigned subchannel. The process willcontinue in this state as long as the single subchannel 300 issufficient for maintaining the required data transfer and/or is beingutilized. However, if the input buffer should become empty, such asnotified by the data handler 426, then the process will proceed to astate 510. In this state 510, the subchannel will remain assigned in theevent that data traffic again resumes. In this case, such as when theinput buffer begins to once again become full and data is again ready totransmit, then the process returns to state 508. However, from state 510should a low traffic timer expire, then the process proceeds to state512 in which the single subchannel 300 is released. The process thenreturns to the idle state 502. In state 512, if a queue request ispending from states 506 or 516, the subchannel is used to satisfy suchrequest instead of releasing it.

[0063] Returning to state 508, if instead the contents of the inputbuffer are beginning to fill at a rate which exceeds a predeterminedthreshold indicating that the single subchannel 300 is insufficient tomaintain the necessary data flow, then a state 514 is entered in whichmore subchannels 300 are requested. A subchannel request message isagain sent over the control channel 440 or through a subchannel 300already allocated. If additional subchannels 300 are not immediatelyavailable, then a pacing state 516 may be entered and the request may beretried by returning to state 514 and 516 as required. Eventually, anadditional subchannel will be granted and processing can return to state508.

[0064] With the additional subchannels being now available, theprocessing continues to state 518 where data transfer may be made on amultiple N of the subchannels. This may be done at the same time througha channel bonding function or other mechanism for allocating theincoming data among the N subchannels. As the input buffer contentsreduced below an empty threshold, then a waiting state 520 may beentered.

[0065] If, however, a buffer filling rate is exceeded, then state 514may be entered in which more subchannels 300 are again requested.

[0066] In state 520, if a high traffic timer has expired, then one ormore of the additional subchannels are released in state 522 and theprocess returns to state 508.

[0067]FIG. 6 is a block diagram of the components of the base stationequipment 170 of the system 100. These components perform analogousfunctions to those as already described in detail in FIG. 4 for thesubscriber unit 101. It should be understood that a forward link 620 andreverse link 630 are required for each subscriber unit 101 or 102needing to be supported by the base station 170.

[0068] The base station forward link 620 functions analogously to thereverse link 420 in the subscriber unit 100, including a subchannelinverse multiplexer 622, voice data detection 623, voice decoder 624,data handler 626, and ISDN spoofer 622, with the understanding that thedata is traveling in the opposite direction in the base station 170.Similarly, the base station reverse link 630 includes componentsanalogous to those in the subscriber forward link 430, including an ISDNspoofer 632, voice data detection 633, voice decoder 634, data handler636, and subchannel multiplexer 638. The base station 170 also requiresa CPU controller 610.

[0069] One difference between the operation of the base station 170 andthe subscriber unit 101 is in the implementation of the bandwidthmanagement functionality 243. This may be implemented in the CPUcontroller 610 or in another process in the base station 170.

[0070] A high level description of a software process performed bydynamic channel allocation portion 650 of the bandwidth management 243is contained in FIG. 7. This process includes a main program 710, whichis continuously executed, and includes processing port requests,processing bandwidth release, and processing bandwidth requests, andthen locating and tearing down unused subchannels.

[0071] The processing of port requests is more particularly detailed ina code module 720. These include upon receiving a port request, andreserving a subchannel for the new connection, preferably chosen fromthe least utilized section of the radio frequency bandwidth. Once thereservation is made, an RF channel frequency and code assignment arereturned to the subscriber unit 101 and a table of subchannelallocations is updated. Otherwise, if subchannels are not available,then the port request is added to a queue of port requests. An expectedwaiting time may be estimated upon the number of pending port requestsand priorities, and an appropriate wait message can be returned to therequesting subscriber unit 101.

[0072] In a bandwidth release module 730, the channel bonding functionexecuting in the multiplexer 622 in the forward link is notified of theneed to release a subchannel. The frequency and code are then returnedto an available pool of subchannels and a radio record is updated.

[0073] The following bandwidth request module 740 may include selectingthe request having the highest priority with lowest bandwidthutilization. Next, a list of available subchannels is analyzed fordetermining the greatest available number. Finally, subchannels areassigned based upon need, priority, and availability. A channelbandwidth bonding function is notified within the subchannel multiplexer622 and the radio record which maintains which subchannels are assignedto which connections is updated.

[0074] In the bandwidth on demand algorithm, probability theory maytypically be employed to manage the number of connections or availableports, and the spectrum needed to maintain expected throughput size andfrequency of subchannel assignments. There may also be provisions forpriority service based upon subscribers who have paid a premium fortheir service.

[0075] It should be understood, for example, that in the case of asupporting 128 kbps ISDN subscriber unit 101 that even more than 16×8kbps subchannels may be allocated at a given time. In particular, onemay allow a larger number, such as 20 subchannels, to be allocated tocompensate for delay and reaction in assigning subchannels. This alsopermits dealing with bursts of data in a more efficient fashion such astypically experienced during the downloading of Web pages.

[0076] In addition, voice traffic may be prioritized as against datatraffic. For example, if a voice call is detected, at least onesubchannel 300 may be active at all times and allocated exclusively tothe voice transfer. In that way, voice calls blocking probability willbe minimized.

EQUIVALENTS

[0077] While this invention has been particularly shown and describedwith references to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention as defined by the appended claims.

[0078] For example, instead of ISDN, other wireline digital protocolsmay be encapsulated by the EW[x] protocol, such as xDSL, Ethernet, andX.25, and therefore may advantageously use the dynamic wirelesssubchannel assignment scheme described herein.

[0079] Those skilled in the art will recognize or be able to ascertainusing no more than routine experimentation, many equivalents to thespecific embodiments of the invention described specifically herein.Such equivalents are intended to be encompassed in the scope of theclaims.

What is claimed is:
 1. For use with a cellular digital communicationnetwork having a base station and a plurality of subscriber units servedthereby, said cellular digital communications network including acontrol channel by way of which digital signal transmission channels areassignable for communication sessions for said subscriber units, amethod of allocating bandwidth to said subscriber units for said digitalsignal transmission channels comprising the steps of: a) in response toa subscriber unit's request for a digital signal transmission channel,allocating a portion of said available bandwidth for use by saidsubscriber unit for said digital signal transmission channel during acommunication session; and b) in the absence of a presentation ofdigital communication signals by said subscriber unit for a prescribedperiod of time during said communication session, deallocating saidportion of said available bandwidth from use by said subscriber unitwhile maintaining the appearance of a continuous connection for saidcommunication session.
 2. For use with a cellular digital communicationnetwork having a base station and a plurality of subscriber units servedthereby, said cellular digital communications network including acontrol channel by way of which digital signal transmission channels areassignable for communication sessions for said subscriber units, amethod of allocating bandwidth to said subscriber units for said digitalsignal transmission channels comprising the steps of: a) in response toa subscriber unit's need to transmit digital communication signals,allocating a portion of said available bandwidth that is selected to theextent possible for meeting said subscriber unit's need, for use by saidsubscriber unit during a communication session; and b) in the absence ofa presentation of digital communication signals by said subscriber unitfor a prescribed period of time during said communication session,deallocating a prescribed portion of said selected portion of saidavailable bandwidth from said subscriber unit and, instead making saidprescribed portion of said selected portion of said available bandwidthavailable for use by another subscriber unit.